Physical and Chemical Papers. 91 



in the cultivated soils than in the virgin soils. Chemically, 

 carbon is the more active element. As organic matter becomes 

 old it becomes more inert. The chemical changes are slower 

 and the response of the soil is more sluggish. 



Column 6 gives the ratio of nitrogen to carbon in organic 

 matter. The widest ratio is found in virgin soils and the nar- 

 rowest in the cultivated soils. The average of the native soils 

 is 1 :12 and that of the cultivated soils is 1 :11.1. What is the 

 significance of this ratio ? 



E. J. Russel states, in his book "Soil Conditions and Plant 

 Growth," that the ratio between nitrogen and carbon in stubble 

 is 1 :40 and in legumes 1 :25. Most of the organic matter in 

 Kansas soils has come from the prairie grass. A number of 

 samples of prairie hay analyzed at the chemical department of 

 the Experiment Station have shown an average nitrogen con- 

 tent of 0.85 per cent. This is a very low nitrogen content, and 

 would compare very well with the stubble to which Russel re- 

 fers. As there are some native legumes, this would influence 

 the ratio. An assumption that the ratio of nitrogen to carbon 

 in the native vegetation w^as 1 :3G would not be an unfair 

 assumption. If the ratio of nitrogen to carbon in virgin soil is 

 1:12, it means that it would have taken three pounds of 

 native vegetation for each pound of organic matter found in 

 the soil, provided that there had been no loss of nitrogen in 

 the process of transforming the native vegetation into such 

 organic matter as is found in the soil. But it does not require 

 any extensive study of the organic chemical changes which go 

 on in the soil to know that great losses do occur. 



This discussion is made for the purpose of showing the 

 enormous amount of native vegetation it has taken to produce 

 the organic matter in the soil, and in this discussion we leave 

 out that present below the surface soil, and this in the aggre- 

 gate would amount to about twice that in the surface soil. 

 Most of the native prairie soils in Kansas contain over 100,000 

 pounds, or fifty tons, of organic matter in the surface soil of 

 one acre seven inches deep. On the basis of the above dis- 

 cussion, which is based on chemical facts — and the estimate is 

 less than what is known to actually take place — it has taken 

 more than 150 tons of native vegetation to produce the organic 

 matter found in our native prairie soils. If, then, over one- 

 third of this organic matter has been lost from our soils after 



